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Discussion Starter · #1 ·
I have a small block chevy 383 stroker. It has a holley 670 street avenger carb, electric choke. Carb has been rebuilt, complete tune up not too long ago, new distributor. Runs good when warm and start right up when weather is warm. On cold (below 40) days, pump gas twice, hit the key, it starts, then stalls. I have to do this about 8 times before it stays running. Any suggestions?
 

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Try not pumping first. Let it crank a little to fill the carb. When it starts to fire, stop cranking and pump once fully but slowly. Winter gas has to be so volatile that a carb with open element breather lets bowls dry out via the vent while the pump well retains that one pump worth. About two seconds. Plus ethanol gas rots the hose between tank and line.

Theres one way to demonstrate / debunk / diagnose. Prime the carb. If no change, I was wrong. I don't use a choke but if the carb is full she will start.
 

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throw that carb away
the wimpiest 383 needs a 750
the 670/770 avenger series are in dire need of major changes to work well. Most everyone just throws them away. Give your engine specs and driving style and get a few ideas here for replacement. I mostly use performance carbs (x pumpers) super easy to tune
 

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Normally if your vehicle is ran everyday then starting it up in cold weather if your choke is set about right then it should fire right up after a few pump shots. Wit the electric choke I have found out that even if its on the right setting for what your engine likes and you have not driven it a few days that if you give it a few pump shots and you fire it up and it will run for a few seconds and then quit and then you give a few more pump shots then it fires up and sort of struggles then at that point and time the electric choke coil had opened up the choke flap enough to the point that your not getting much of the choke operation as the coil has opened up the choke plate enough and also the fast idle cam has went down enough to allow for the primary throttle blades to not sit much higher anymore to pull a little more fuel from the transfer slot.

The electric choke is nice but if after you have given it a few pump shots and then it fires up and then quits and you have a few more pump shots again and it fires back up and runs for a few then goes off again and then you give another pump shot then sometimes because of fighting with it to get it started it can end up flooding it and make it hard to run at first and by that time the choke has opened up so much that you no longer have the choke working to allow it to run.

This is why I switched out to a manual choke. I have had on days to where I would give about two pump shots and it would start up and keep running just fine and other days to where the temperature was really super cold and I had my choke already as rich as I could get it without being too rich and if I did not give a right amount of pump shots and then tried to get it started it would run for a few seconds and then die out because I did not give enough so I would give a few more shots and then it would run and sometimes it would not as it would just depend on things and the electric choke is kind of picky at times depending on the temperate and in some temperatures it works fine and in some it is kind of borderline to either open a little to fast or kind of not fast enough.

With a manual choke I can just pull my cable open and then give what it needs and fire it up and when its starting to warm up I just push the choke cable back in and open the choke flap open and then its good to go. Some times when you have them set for say in 40 degree weather you might have to readjust it for even colder temperatures as that is the thing with them as they can be fine in one range of temperature but not in another range.

The Holley street avengers are not junk carbs but just like any carb they need tuned and worked out to what your engine needs just like everything else. Its all about the tune and calibrating the carb itself and takes more then just turning some screws. Don't let others make you feel bad about what your using. Nothing wrong in my opinion in using a Holley 670 on a 383 if its a mild street cruiser. If you want every ounce of power you can get then get a 750 or bigger but it depends on what your happy with. Only problems with the Street avengers is there calibration out of the box but like any carb it can be fixed and tuned to run very well if you know what your doing. The Quick fuel carbs a lot better though with better tuning options.Just my two cents.
 

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To make it in simpler form when you turn on the key the coil will start to heat up and open up the choke flap and you pump the gas pedal a few times to prime the engine and get it to start up. The thing is depending on the temperature and where you have your choke set at, while your cranking and the coil is expanding and opening up the choke plate it only allows a certain time frame to get the engine just enough fuel to get it to stay running with the choke operating and its not opened up to much but if you have given it too little fuel and it quits and by the time you give it some more pump shots then at times it can be at the point with turning over the engine and to many pump shots it is then flooded and the choke flap is open up to much to get the effect of the choke and its open up to far at that point.

As the engine is trying to run and with the choke being in operation it will pull extra amount of fuel into the motor and if it quits a few times it will not take much to end up flooding it and its a balance of not to many pump shots or not to little. That is the downside of using an electric choke versus a manual which you can control yourself.
 

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Discussion Starter · #11 ·
Try not pumping first. Let it crank a little to fill the carb. When it starts to fire, stop cranking and pump once fully but slowly. Winter gas has to be so volatile that a carb with open element breather lets bowls dry out via the vent while the pump well retains that one pump worth. About two seconds. Plus ethanol gas rots the hose between tank and line.

Theres one way to demonstrate / debunk / diagnose. Prime the carb. If no change, I was wrong. I don't use a choke but if the carb is full she will start.
Will have to try that. Thanks.
 

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Discussion Starter · #12 ·
Normally if your vehicle is ran everyday then starting it up in cold weather if your choke is set about right then it should fire right up after a few pump shots. Wit the electric choke I have found out that even if its on the right setting for what your engine likes and you have not driven it a few days that if you give it a few pump shots and you fire it up and it will run for a few seconds and then quit and then you give a few more pump shots then it fires up and sort of struggles then at that point and time the electric choke coil had opened up the choke flap enough to the point that your not getting much of the choke operation as the coil has opened up the choke plate enough and also the fast idle cam has went down enough to allow for the primary throttle blades to not sit much higher anymore to pull a little more fuel from the transfer slot.

The electric choke is nice but if after you have given it a few pump shots and then it fires up and then quits and you have a few more pump shots again and it fires back up and runs for a few then goes off again and then you give another pump shot then sometimes because of fighting with it to get it started it can end up flooding it and make it hard to run at first and by that time the choke has opened up so much that you no longer have the choke working to allow it to run.

This is why I switched out to a manual choke. I have had on days to where I would give about two pump shots and it would start up and keep running just fine and other days to where the temperature was really super cold and I had my choke already as rich as I could get it without being too rich and if I did not give a right amount of pump shots and then tried to get it started it would run for a few seconds and then die out because I did not give enough so I would give a few more shots and then it would run and sometimes it would not as it would just depend on things and the electric choke is kind of picky at times depending on the temperate and in some temperatures it works fine and in some it is kind of borderline to either open a little to fast or kind of not fast enough.

With a manual choke I can just pull my cable open and then give what it needs and fire it up and when its starting to warm up I just push the choke cable back in and open the choke flap open and then its good to go. Some times when you have them set for say in 40 degree weather you might have to readjust it for even colder temperatures as that is the thing with them as they can be fine in one range of temperature but not in another range.

The Holley street avengers are not junk carbs but just like any carb they need tuned and worked out to what your engine needs just like everything else. Its all about the tune and calibrating the carb itself and takes more then just turning some screws. Don't let others make you feel bad about what your using. Nothing wrong in my opinion in using a Holley 670 on a 383 if its a mild street cruiser. If you want every ounce of power you can get then get a 750 or bigger but it depends on what your happy with. Only problems with the Street avengers is there calibration out of the box but like any carb it can be fixed and tuned to run very well if you know what your doing. The Quick fuel carbs a lot better though with better tuning options.Just my two cents.
My son has only had this truck for 6 months. I've never messed must with carbs, just on small engines. But I'm learning. As far as I can tell it's just a stock cam and stock heads. I think sometimes the jetting might be too rich but haven't pulled any plugs to see.
 

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Discussion Starter · #13 ·
To make it in simpler form when you turn on the key the coil will start to heat up and open up the choke flap and you pump the gas pedal a few times to prime the engine and get it to start up. The thing is depending on the temperature and where you have your choke set at, while your cranking and the coil is expanding and opening up the choke plate it only allows a certain time frame to get the engine just enough fuel to get it to stay running with the choke operating and its not opened up to much but if you have given it too little fuel and it quits and by the time you give it some more pump shots then at times it can be at the point with turning over the engine and to many pump shots it is then flooded and the choke flap is open up to much to get the effect of the choke and its open up to far at that point.

As the engine is trying to run and with the choke being in operation it will pull extra amount of fuel into the motor and if it quits a few times it will not take much to end up flooding it and its a balance of not to many pump shots or not to little. That is the downside of using an electric choke versus a manual which you can control yourself.
I have thought about that. Maybe a better thought would be to find a power source that only has power when the engine is running.
 

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If you are using pump gas (ethanol) 10%, then I would start there first. Find a station that has pure gas.
I have seen a lot of 10% Ethanol gas that won't light in a puddle on the floor.
I always thought that if 10% of what you want to burn requires twice as much to run, then you are 5% lean from the get go.
 

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Discussion Starter · #15 ·
throw that carb away
the wimpiest 383 needs a 750
the 670/770 avenger series are in dire need of major changes to work well. Most everyone just throws them away. Give your engine specs and driving style and get a few ideas here for replacement. I mostly use performance carbs (x pumpers) super easy to tune
This is what I have to work with. The rest of the truck needs money more than a 99% functioning carb. I will do what I can with this for now. Basically everything is stock except for the carb and intake.
 

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Discussion Starter · #16 ·
If you are using pump gas (ethanol) 10%, then I would start there first. Find a station that has pure gas.
I have seen a lot of 10% Ethanol gas that won't light in a puddle on the floor.
I always thought that if 10% of what you want to burn requires twice as much to run, then you are 5% lean from the get go.
Good point. I do know about alcohol. We race go karts the burn strait methanol.
 

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I have a Quadrajet on my 350 with aluminum heads and intake, and it’s quite cold blooded until it’s warmed up.

I’ve found that it idles better if I verify the transfer slot exposure is square, and then adjust the idle mixture a little richer than optimum idle vacuum, (about 1/4 to 1/2 turn richer). Highest vacuum was at about 13.5 AFR, but I now show about 12.5. It still needs to warm up for several minutes, but at least idles smooth enough to not die during warm up.
 

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The Holley 670 street avenger is more then enough for a bone stock motor even if its a 383. You don't always have to have the bigger carb on a mild build to get it to run good and perform well especially if you don't race it and only cruise with it. I myself have a 350 small block that has the works done to it and I use a 600 to 650 cfm rated carburetor on it and have used a 750 cfm rated carb on it before and the only difference is on the top end of things past 5000 rpm and I don't race or take my truck to the track. Some folks are just die hard set in there ways that a certain size cam or a carb is needed and there is not other options that are acceptable and give others a hard time about it.

I always give advice on peoples builds but don't trash them if they decide on something slightly different that is not way over board or way under or mismatched really bad. Stick with your 670 and get it running and tuned and adjusted well and get it to work with this build and you can still have a very nice running 383.

I respect others opinions on size of things but I also have my own and some guys just are set and there is nothing changing that and that is ok as we all have what we like but I always say that is why there is different heads and cams and other parts you can choose from and if your doing something slightly different and its still within reason then to me there is nothing wrong with it and its still matched good within reason. I am conservative on things and do leave some power on the table but I still have plenty on my plate to use and get from my build which is more then enough for what I do with my ride.

Just keep at it and stick with what you have and work on other things and worry about a different carb size in the future if you decide to go that route. Focus on the important things first such as getting it running good and then leave that for now and then whatever else you have for plans focus on that and go from there. Setting up an electric choke can be a picky thing at times as on some days if you set it at a certain point it can be too rich and then others it might be to lean and open up to fast. Depending on what alternator your using there is a spot on the alternator that you can hook up your electric choke up to and it will not allow the choke to get power until you reach a certain rpm and the alternator will start to generate power and charge the battery and then the choke will come on.

On that part it gives you time to crank your engine over without it opening up to fast in certain situations since it won't be powered up until you get it running steady and over about 1300 rpm give or take a hair. Be careful on the alternator hookup as one wire is constant and you don't want it there and the other wire is the one you want as it will only energize once the rpms are up enough once the engine is running steady. Its one of the spade connectors on the alternator but which one I forget as its been a while. Just make sure to install an inline fuse when hooking it up.
 

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Here is my scenario or opinion on small carbs:
90% of the time you would have no idea that you are anything but fast. @ 1/2-2/3 throttle the car is more than fun to drive. Tires spin freely, engine response is excellent. So what happens when you water pump that small carb? It accelerates a little quicker hitting an early redline,,, now shift. Probably tires break loose or at least leave a 15' stripe at 50 mph.
Now my engine has a moderate cam and a 950 cfm carb. I have similar low rpm response perhaps even slightly less. (slightly) I have way more hp/tq but higher up the rpm range. The problem with mine is when I water pump the throttle @4000 rpm all hell breaks loose I shift around 57 mph and my tires go instantly to 88 mph on the rev limiter.
Choose you monster. Cute little one or beast or anything in between
 

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If you are using pump gas (ethanol) 10%, then I would start there first. Find a station that has pure gas.
I have seen a lot of 10% Ethanol gas that won't light in a puddle on the floor.
I always thought that if 10% of what you want to burn requires twice as much to run, then you are 5% lean from the get go.
Don't agree at all. Even at 85 percent, when the carb is right, it'll fire at -20 below.
Ive been playing with E85 for a few years and don't ANY cold start problems at any temps.
 
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